1. Field of the Invention
The present invention relates to a rewritable disk advantageously applicable to a magneto-optic disk of a type allowing additional writing or rewriting and hardware (disk apparatus) for the same.
2. Description of the Related Art
Of magneto-optic disks, rewritable disks on which data can be rewritten many times are known. Such a magneto-optic disk 10 has, as shown in FIG. 10, tracks (concentric tracks) formed thereon along concentric circles with respect to its chucking hole 12, and each track has a plurality of sectors 16 formed in the circular direction at a predetermined pitch, the sectors storing video data, audio data, and other data.
Between the sectors 16, 16, there is provided an edit gap (EG) 18 as shown in FIG. 11. The edit gap 18 is a clearance area which is provided for preventing data to be written in one sector from being written into the adjoining sector even if there exists an eccentricity produced at the time of disk chucking. Usually, the edit gap 18 is designed to have a length W around 1% of the length L of the sector 16 in the circular direction, because most of eccentricities caused by the eccentric chucking can be absorbed by the edit gap 18 arranged to have such length.
An apparatus for the rewritable magneto-optic disk chiefly recording and reproducing image information is connected with various image devices through an interface and video signals output from the devices are digitally recorded and reproduced in the apparatus. Since the signals are video signals, they are transmitted at the rate of 120Mbps to 540Mbps and it is required that the signals are recorded over a period from several minutes to dozens of minutes. Therefore, the magneto-optic disk for the described use is required to allow recording of considerably high density. Hence, a high degree of accuracy in repeated recording is required of the magneto-optic disk also out of necessity for exchangeability.
However, in the case of the magneto-optic disk 10 employing such a format as shown in FIG. 10, the data length of the edit gap 18 is designed to include a sufficient length of clearance, and hence the total length of the edit gaps 18 amounts to a considerable length even if the length W of each gap is around 1% of the length of the sector 16, and this has been a cause preventing achievement of high-density recording.